Electric transformer



Dec. 30, 1930. s. z 5 FERRANTl/ 1,786,899

ELECTRIC TRANSFORMER Filed Feb. 1926 I/WcA/ 7012 By. 727% y 46% v 7 HM.

Patented Dec. 30, 1930 UNITED STATES,

ATENTO H SEBASTIAN ZIANI 1m FERRANTI, or HOLLINWOOD, ENGLAND, ASSIGNOR rormmanrrr,

.- l LIMITED, or noLLmwooD, ENGLAND I j ntncriuc TRANSFORMER I Application filed February 11, 1926, SerialNo.

in connection with wireless telephony i or 5 telegraphy, and has for its object to provide improved or simplified constructions.

The invention consists in a radio frequency or audio frequency electric transformer embodying a continuous (jointless) winding wound in sections which are mutually separated by air spaces.

The invention also consists in a radio or audio frequency electric transformer as set forth above, including a plurality of bobbins each bearing sets of projecting portions, certain of the projections on the inner bobbin or inner; bobbins being adapted to register with certain of the projections on the outer bobbin or outer bobbins for the purpose described. i 3 t a i The invention also consists in a radio frequency or audio frequency electric transformer as set forth abovejwherein the bobbin or bobbins is constituted'as an openwork framework with separating members for dividing the continuous winding into sections.

The invention also consist in a radio frequency or audio frequency electric transformer as set forthabove'including preferably bifurcated pegsfixed in or otherwise provided in the bobbin hub or flanges and serving as terminal posts. 7

' The invention also'con-sistsin a radio frequency or audio frequency electric transformer as set forth in the preceding paragraph including notches formed in the bobbin adjacent the pegs and serving to accommodate the wire atthese regions and protect it from mechanical damag vention.

The invention also consists in a radio fr e- 87,691, and in Great fBritain March 12, 1925,

or rings and integral pegs are provided at points of intersection'in order'to divide the winding into sections.

The invention also consists in aradio frequency or audio frequency electric transformer embodying a plurality of bobbins wound with continuous (jointless) windings in mutually separated sections, the ends of the 'windings being mechanically supported on pegs and being entirely shielded from mechanical damage for the purpose described.

The invention further consists in radio or'audio frequency electric transformers, substantially as hereinafter described with reference to the'accompanying drawings.

fbobbin in accordance; with the present in- 'vention;,r

Figure .2is an end elevational view thereof partly in section, and

FigureB is an enlarged fragmental view of part of the bobbin of Figure 1; 7

Figures l, 5 and 6 illustrate respectively in section, plan and "end elevations a convenient arrangement of bobbins and electrical connections in accordance with the present inl carrying the invention into effect in one form as illustrated by way of example in Fig ures '1 and 2 as applied to'an intervalve audio frequency transformer, there is providedas regards the primary winding-a bobbin of insulating material, the bobbin being formed as a cylinder perforated by a large number of square openings a. The bobbin comprises a series of longitudinal ribs b intersecting two rings '0 and two flanges d, the whole constituting an integral openwork framework or:cage. 7 it In the particular example now being described the primary winding is intended to be spaced into three axially spaced sections and in order to accommodatethese sections the openwork cylindrical frame so far deintegral flanged at either end, Two intermediate sets of integral-and radially protrudescribed is furnished with two, rings 0 and'an ing projections or pegs are also provided. The said projections or pegs which conveniently may be of square cross section or as cylindrical pegs e as shown preferably protrude from the junctions between the longitudinal ribs Z) and rings a and constitute broken flanges for the mutual separation of adjacent coil sections of the continuous winding to be described below. The end flanges may also be formed as sets of radially protruding pegs if desired but it is preferred to form these as continuous flanges as shown, thus affording greater mechanical protection for the windings and increasing mechanical rigidity of the bobbin as a whole. Again the intermediate sets of projections or pegs may be replaced by continuous radial flanges which embody at intervals on both sides axiallyprojecting radial ridges, thus providing greater mechanical strength at the cost of slightly inferior air spacing between adjacent coil sections. A metal pin is secured (or moulded in) to each end flange, the flange being suitably thickened locally if necessary to accommodate the pins.

Such a construction is indicated in Figure 3 wherein a thickened lug f has moulded in it a bifurcated metal pin 9. A narrow notch h is formed as shown in order to accommodate the winding end as explained below. In applying the winding it is bared of insulation at its end and this end is inserted in the bifurcation in the pin 7 and lapped once or twice around the pin. The wire is then laid in the notch h and applied as a continuous winding on section A of the bobbin. The wire is then passed diagonally between two protruding projections or pegs e (or through a slot in cases where these pegs are substituted by ribbed flanges) and the second section B of the winding laid. Finally the wire is similarly passed through the second intermediate set of protruding projections e (or slotted flange), and the third winding section C laid. The wire is then laid in the notch h, bared of insulation, twisted around the second metal pin 9 and inserted in the bifurcation therein. This primary bobbin coil is now complete.

It will be appreciated that this winding is continuous from end to end, no joints being needed between the wire constituting the sections and the usual end connecting turns of stouter gauge wire are entirely dispensed with since the ends of wire of the winding themselves are supported on the pins and are entirely protected against mechanical injury by their disposition in the notches provided.

A similar bobbin and a similar procedure of coil winding is adopted as regards the secondary coil or coils, each such coil when formed being complete in itself.

Thus the formation and erection of the desired coils is greatly facilitated, since any desired number of coil units may be threaded one within the other and the necessary pigtail connecting leads soldered to the metal pegs g and coil ends which are mechanically supported thereon.

The bobbin units may be handled without risk of injury and each possesses but low self capacity.

It is to be understood that the construction described above is given by way of example only and may be modified. For instance, it is not necessary to have the same number of winding sections on the primary and secondary coils; it is preferred in fact, as regards audio frequency intervalve transformers, to form the secondary winding with a greater number of sections than the primary and to form the latter on two separate bobbins, one of which is threaded within the secondary bobbin (i. e. next to the core) and the other of which is threaded over the secondary bobbin.

An example of such construction is illustrated in. Figures 4;, 5 and 6, in which j and m are the primary bobbins and k the secondary bobbin. The electrical connections to the bobbin pegs are seen in Figures 5 and 6, g 9 being the connecting leads to the secondary winding and 1' a" being the connecting leads to the primary windings. The lead 8 represents the connection between the two separate primary windings.

It is desirable to so arrange the number of radial pegs e on the respective bobbins that certain of these on one bobbin come into re ister with certain of these on the adjacent bobbin as to prevent any load being taken. on the windings themselves. For example, as illustrated in Figure 4 the innermost bobbin j is provided with nine axial rows of radial pegs, the intermediate bobbin ]c with twelve axial rows and the outermost bobbin m with fifteen axial rows. Thus at intervals of 120 (at n, 0 and p, Figure 4) a row on all bobbins fall into register and thus provide mutual support.

It is not essential that actual openin s (a, Figure 1) be provided although this is neficial in the reduction of self capacity. For example, bobbins may be formed in accordance with the present invention as true cylinders, i. e. sleeves of insulating material with end flanges and salient circular and longitudinal ribs. Such construction is specially appropriate for the innermost bobbin of a series as this facilitates the insertion of the core laminae.

I claim:

1. An electric transformer including in combination an inherently rigid openwork bobbin framework formed on a plurality of longitudinal ribs, two end flanges and one or more intermediately disposed rings, a plurality ofradial projections disposed at points of intersection of the ribs and rings, a ointless winding wound in sections upon said bobbin, said sections being mutually separated axially by air spaces and by said radial projections, a plurality of metal soldering lugs rigid with said bobbin serving as terminal posts for the winding ends, and notches formed in said bobbins adjacent said soldering lugs serving to accommodate and mechanically to shield the wire.

2. An electric transformer includin in combination a rigid integral'openwork obbin framework constituted by a plurality of 1 longitudinal ribs, two end flanges, a plurality of intermediately disposed rings between said flanges, a plurality of radial projections projecting from intersections between the ribs and the rings, a jointless winding wound in sections upon said framework, said sections being mutually separated axially by air spaces and by said radial projections, and a plurality of metal soldering lugs rigid with said framework serving as terminal posts for the winding ends.

In testimony whereof I have signed my name to this specification.

SEBASTIAN ZIANI on FERRANTI. 

